Photovoltaic cell with a specific arrangement of energy collectors, and method for producing such a cell

Abstract

A photovoltaic cell (1) including a first front collector layer (4), an amorphous silicon layer (6) on the first layer (4) and a second conductive layer (8) on the amorphous silicon layer (6). Electrical connection of the second conductive layer (8) to the first layer (4) is made through the amorphous silicon layer (6) at the periphery of the photovoltaic cell, the electrically conductive layer (8) comprising a positive peripheral bus (8′), which is connected to the TCO first layer (4) and to at least one positive connection terminal at one end of the positive peripheral bus, and a negative peripheral bus, which is connected to a negative connection terminal, and the positive and negative peripheral buses being asymmetrical relative to one another, with the positive peripheral bus being longer than the negative peripheral bus.

The invention claimed is: 
     
         1 . A photovoltaic cell ( 1 ) configured to be arranged on an inner surface of a transparent glass or on a dial of a portable object, said photovoltaic cell ( 1 ) comprising a first transparent conductive layer (TCO) constituting a front collector layer ( 4 ), an amorphous silicon layer ( 6 ) on the front collector layer ( 4 ) and a conductive layer ( 8 ) on the amorphous silicon layer ( 6 ), constituting a rear collector, an electrical connection from the conductive layer ( 8 ) to the front collector layer ( 4 ) being made through the amorphous silicon layer ( 6 ),
 wherein the electrical connection of the conductive layer ( 8 ) to the front collector layer ( 4 ) is made through the amorphous silicon layer ( 6 ) at the periphery of the photovoltaic cell, wherein the conductive layer ( 8 ) comprises a positive peripheral bus ( 8 ′), which is connected to the front collector layer ( 4 ) and to at least two positive connection terminals ( 8 ′ a ,  8 ′ b ) at ends of the positive peripheral bus, and a negative peripheral bus, which is connected to a negative connection terminal, and wherein the positive and negative peripheral buses have different lengths along the periphery of the photovoltaic cell, with the positive peripheral bus having a greater length than the negative peripheral bus, and   wherein the at least two positive connection terminals ( 8 ′ a ,  8 ′ b ) pass through the amorphous silicon layer ( 6 ) and contact the front collector layer ( 4 ), the at least two positive connection terminals ( 8 ′ a ,  8 ′ b ) being connected in parallel.   
     
     
         2 . The photovoltaic cell ( 1 ) according to  claim 1 , wherein a thickness and width of the positive peripheral bus are substantially identical to a thickness and width of the negative peripheral bus, and wherein the length of the positive peripheral bus is at least more than 10 times greater than that of the negative peripheral bus. 
     
     
         3 . The photovoltaic cell ( 1 ) according to  claim 1 , wherein the electrical connection of the electrically conductive layer ( 8 ) to the front collector layer ( 4 ) is made through the amorphous silicon layer ( 6 ) over the entire length of the positive peripheral bus of the conductive layer ( 8 ), and
 wherein the conductive layer ( 8 ) is a metal layer.   
     
     
         4 . The photovoltaic cell ( 1 ) according to  claim 3 , wherein the metal layer is a layer of aluminium. 
     
     
         5 . The photovoltaic cell ( 1 ) according to  claim 3 , wherein the photovoltaic cell is a circular cylinder in plan view, wherein the positive peripheral bus describes a total circular arc of 330° with a peripheral electrical connection to the front collector layer ( 4 ) over its entire length, wherein the positive peripheral bus terminates on a first side in a first positive connection terminal ( 8 ′ a ), and on a second opposite side in a second positive connection terminal ( 8 ′ b ), and wherein the negative peripheral bus comprising the negative connection terminal follows an arc of a circle of less than 30° on each side of the first positive connection terminal ( 8 ′ a ) of the positive peripheral bus and the second positive connection terminal ( 8 ′ b ) of the positive peripheral bus. 
     
     
         6 . The photovoltaic cell ( 1 ) according to  claim 3 , wherein the photovoltaic cell is a circular cylinder in plan view, wherein the positive peripheral bus describes a total circular arc of 350° with a peripheral electrical connection to the front collector layer ( 4 ) over its entire length, wherein the positive peripheral bus terminates on a first side in a first positive connection terminal ( 8 ′ a ), and on a second opposite side in a second positive connection terminal ( 8 ′ b ), and wherein the negative peripheral bus comprising the negative connection terminal follows an arc of a circle of less than 10° on each side the first positive connection terminal ( 8 ′ a ) of the positive peripheral bus and the second positive connection terminal ( 8 ′ b ) of the positive peripheral bus. 
     
     
         7 . The photovoltaic cell ( 1 ) according to  claim 1 , wherein the front collector layer ( 4 ), the amorphous silicon layer ( 6 ), and the conductive layer ( 8 ) are produced on an inner face of a glass of the portable object, so as to form a photovoltaic cell assembly with the glass of the portable object ( 2 ) forming part of the photovoltaic cell. 
     
     
         8 . The photovoltaic cell ( 1 ) according to  claim 1 , wherein the conductive layer ( 8 ) is a metal layer which comprises, in a central portion connected to a negative terminal of the negative peripheral bus, openwork parts so as to render the photovoltaic cell semi-transparent. 
     
     
         9 . A method for producing a photovoltaic cell ( 1 ) according to  claim 1 , wherein the method comprises steps of:
 depositing an amorphous silicon layer ( 6 ) on a first transparent conductive layer (TCO) constituting a front collector layer ( 4 ),   making an opening ( 12 ) through the amorphous silicon layer ( 6 ) to give access to the front collector layer ( 4 ),   depositing an electrically conductive layer ( 8 ) on the amorphous silicon layer ( 6 ), with part of the electrically conductive layer ( 8 ) contacting front collector layer ( 4 ),   making an opening through the amorphous silicon layer ( 6 ) located in a peripheral area of the photovoltaic cell ( 1 ), and   separating the electrically conductive layer ( 8 ) in order to contact the front collector layer ( 4 ) and produce the positive peripheral bus ( 8 ′), and a metal layer connected to the parts of the negative peripheral bus connected to a negative terminal ( 8 ) of the photovoltaic cell, by producing, through the electrically conductive layer ( 8 ), an opening ( 12 ′) in the electrically conductive layer.   
     
     
         10 . The method according to  claim 9 , wherein the electrically conductive layer ( 8 ) is a metal layer that includes aluminium. 
     
     
         11 . The method according to  claim 9 , wherein openwork parts are produced in a central part of the metal layer connected to the negative connection terminal. 
     
     
         12 . The method according to  claim 9 , wherein all of the steps for producing the photovoltaic cell ( 1 ) are carried out on a base layer which is a glass ( 2 ) of a portable object forming part of the photovoltaic cell. 
     
     
         13 . The photovoltaic cell ( 1 ) according to  claim 1 , wherein the electrical connection of the conductive layer ( 8 ) to the front collector layer ( 4 ) is made through the amorphous silicon layer ( 6 ) only at the periphery of the photovoltaic cell. 
     
     
         14 . The photovoltaic cell ( 1 ) according to  claim 13 , wherein the conductive layer ( 8 ) is a metal layer that comprises aluminium.